ADHESION OF PARASITIZED RED-BLOOD-CELLS TO CULTURED ENDOTHELIAL-CELLS- A FLOW-BASED STUDY OF ISOLATES FROM GAMBIAN CHILDREN WITH FALCIPARUM-MALARIA

Adhesion of parasitized red blood cells to vascular endothelium is tho ught to play an important role in the development of the ischaemic com plications associated with severe falciparum malaria. Using a novel, f low-based assay, we have investigated the adhesion of parasitized red blood cells to formalin-fixed human umbilical vein endothelial cells ( HUVEC), for isolates obtained from 32 Gambian subjects with mild or se vere falciparum malaria. Red cells infected with wild strains of Plasm odium falciparum were able to adhere to HUVEC under physiologically re levant flow conditions, but the level of adhesion was highly variable, ranging from 1 to 688 adherent cells per mm(2) of HUVEC. Within isola tes, some adherent parasitized cells remained stationary, whilst other formed less stable interactions and rolled slowly over the cell surfa ce. There was no significant difference in adhesion of parasitized cel ls between isolates obtained from mild or severe cases of malaria, alt hough a subset of isolates did show very high levels of adhesion. The results suggest that there is not a simple relationship between the ad hesion of parasitized cells to cultured endothelial cells (presumably via the receptor ICAM-1) and the clinical severity of the disease, alt hough variation in microvascular adhesion in vivo may still be a deter minant of ischaemic complications.